Anti‐epidermal growth factor receptor‐antibody therapy for treatment of breast cancer

Recent studies demonstrated that tumors overexpressing the epidermal growth factor receptor (EGF‐R, erbB‐1) are associated with poor clinical outcome. This led to the development of a variety of monoclonal antibodies targeting the extracellular domain of this receptor tyrosine kinase. The aim of our study was the evaluation of anti‐EGF‐R antibody EMD 55900 therapy for treatment of breast cancer. On the basis of 299 tumor specimens derived from breast cancer patients, we investigated EGF‐R expression and generated a collective of primary xenotransplants in athymic nude mice. The animals received therapy in 2 treatment schedules to investigate the therapeutic response in early stages of tumor formation as well as on well established tumors. Using 6 different tumors with EGF‐R expression levels between 10–300 fmol/mg total protein, we found a therapeutic effect when the EGF‐R expression of the tumors was at least 40 fMol/mg. On the basis of these experimental data and our EGF‐R expression analysis of breast cancer specimens, we conclude that up to 15% of breast cancer patients could benefit from this monotherapy with EMD 55900. © 2002 Wiley‐Liss, Inc.